Communications networks have evolved from circuit-switched networks such as the Public Switched Telephone Network (PSTN) to packet-switched networks such as the Internet. Packet-switched networks are designed for packet-based communications, such as Voice over Internet Protocol (VoIP). Most networks existing today are either packet-based or circuit-switched. Packet-based and circuit-switched networks have many differences, such as bandwidth availability, that often require the use of different coder/decoder (codec) schemes for voice and multimedia (e.g., video, etc.) communications.
VoIP infrastructures that do not allow users to cell traditional telephone endpoints are of limited value. The bridge between these two worlds is generally done with a network element, such as a VoIP/PSTN gateway. These VoIP/PSTN gateways are used in the telecommunications industry to pass messages and data between different networks. VoIP/PSTN gateways typically only support a limited set of codecs, which means that some communications based on codecs that the gateway does not support will not go through. In addition, these gateways often provide poor quality audio communications caused by the dynamic and sometimes unstable nature of packet-based communications. As a further problem, most of the VoIP services on the market do not encrypt the voice data because the gateways typically cannot encrypt them. In such scenarios, because the gateways are on the public Internet and because the voice data is unencrypted, these communications are insecure and can be intercepted by other people on the Internet. These scenarios result in a poor quality voice experience and/or an insecure voice experience for the users, if the user is even able to complete the communication at all.